With the conventional prior art in these fields, as applied to ferry boats, the boats come into the dock end first guided by pilings or wingwalls, are held in place by mooring lines and/or vessel propulsion, and a ramp hinged on the dock facility is lowered to the main deck of the boat for unloading payload and then raised before the boat departs. The ramps are usually no more than two vehicle lanes wide while the decks of the boats are often several lanes wide. This situation sets up requirements that the boat be fitted with inter-deck ramps and that deck space be devoted specifically to provision for convergence of the several lanes to the one or two used for loading and unloading. Meeting these requirements limits the number of decks which can be feasibly used and lowers the ratio of payload space to total deck space of the boats using such mooring and ramp systems, thus limiting the traffic flow rate capability of the ferry system, especially relative to the speeds and displacements of the boats used in the system. A second aspect of conventional mooring and ramp systems which limits the traffic flow rate capability is that each boat must be unloaded and loaded in sequence, requiring significantly more time per turn around than would be required if loading and unloading were done simultaneously.
U.S. Pat. No. 3,069,862 issued to Ward discloses a floating transfer bridge having a shore end that is pivotably secured for movement in a vertical plane and a seaward end supported by a float which raises and lowers the seaward end of the bridge section as the tides change the water level. Thus, the pivotable movement of the seaward end allows more than one lane of a ferry boat to be aligned therewith. Ward discloses a floating transfer bridge that is, itself, pivotable, and does not disclose a mooring and ramp system which allows a moored boat to be moved laterally relative to the mooring and ramp system.
U.S. Pat. No. 1,913,207 issued to McDougall discloses a boat for transporting vehicles having a plurality of decks and a dock having two sets of tracks, one above the other, for conveying vehicles to and from the vessel. A doubledeck ramp is hingedly attached to the fixed termini of the tracks, with the free end of the ramp registerable with the decks of the vessel. Again, McDougall does not disclose a mooring and ramp system in which the boat, when secured to the mooring and ramp system, is movable laterally relative thereto.
U.S. Pat. No. 3,320,918 issued to Zalejski discloses a combination of a floating dock and a plurality of motorized barges. The floating dock can be moored away from shore and the barges moved between the dock and the shore. Each of the barges can support a quantity of vehicles thereon. Each of the decks provides a space for parking the vehicles.
U.S. Pat. No. 3,326,171 issued to Zade discloses a device for minimizing damages arising from ship collisions which includes a rotatable abutment member mounted on a ship's hull which functions, during the initial contact between a ship and a striking ship, to swerve the bow of the striking ship laterally whereby head-on impact is avoided.
U.S. Pat. No. 2,389,353 issued to Foss discloses a floating dock that is held in position by chains connected to pilings sunk wholly beneath the surface of the ground where it is protected from borers and is not subjected to unsupported strains exerted against the piling transversely thereof. The floating dock is configured to cushion the landing of a boat, thus minimizing damage to the boat and the dock.
U.S. Pat. No. 768,765 issued to Maclean for a device for securing vessels to moorings includes electromagnets located on the boat or a landing and collective armature disposed on the other of the boat and the landing. In this manner, the boat is magnetically secured to the landing.
Russian Patent Publication No. 258048 discloses a ship docking device that is employed where the length of the ship exceeds that of the dock. A directing track has a closed circuit. The directing track may be in channel form with the centering cables connected to shock absorbers. When a ship is brought into or taken out of the dock, each trolley is connected by cables with shock absorbers to the hull of the ship. Capstans are then used to move an endless chain with trolleys along the closed track. Other capstans are used to operate a chain which speeds up their motion as they move along the dock by interaction with teeth of the trolleys.
Accordingly, a need exists for the enhancement of the traffic flow rate capability of a ferry system. Further needs exist for: (1) a mooring and ramp system unaffected by changes in water level caused by tides or other factors, (2) a mooring and ramp system that facilitates simultaneous loading and unloading of boats, and (3) a mooring and ramp system that facilitates use of multi-deck ferry boats.